1. Field of the Invention
The present disclosure relates to a multi-feed antenna, and more particularly, to a multi-feed antenna capable of switching between different feed terminals via a control circuit.
2. Description of the Prior Art
The antenna is utilized for transmitting or receiving radio waves, so as to transmit or to exchange radio signals. Generally speaking, electronic products with communication function of Wireless Local Area Network (WLAN), such as laptops, mobile phones, tablets, or other hand-held devices having communication function, utilize internal antennas for accessing a wireless network. With progress of communication technology, the operating frequencies of different wireless communication systems may be different, for example, a carrier central frequency of Wireless Local Area Network standard 802.11a set by Institute of Electrical and Electronics Engineers (IEEE) is about 5 GHz and a carrier central frequency of IEEE 802.11b is about 2.4 GHz. Therefore, in order to allow users to access different wireless communication network more conveniently, an ideal antenna should be capable of covering different desired frequency bands of different wireless communication network in single antenna. Besides, the size of the ideal antenna should be as small as possible, so as to match the trends of degrading size of the wireless communication device and to integrate the antenna in the wireless communication device.
With the continuously increasing of demand and quality of the wireless communication system, broadband antenna and the multi-band antenna are not only for fulfilling the requirement of bandwidth but for improving the quality of communication, especially for improving the quality of communicating on phones. As to insufficient bandwidth, there are practical difficulties of designing Planar Inverted F antenna (PIFA) with multi frequency bands if multiple desired frequency bands are close. In addition, a coupling on the resonant path of the Planar Inverted F antenna of multi frequency bands complicates the design of Planar Inverted F antenna of multi frequency bands. Generally speaking, a tradeoff between bandwidth and performance of the broadband Planar Inverted F antenna decreases the area of antenna. As to poor quality of communicating on the phones, the performance of the antenna of mobile phone could degrade because of effects of human body, such as the methods/position of hand holding or the antenna is too close to human body, and could degrade the quality of communication.